The present invention relates to an electron emitter, and more particularly to an electron emitter constructed from an insulating nitride compound.
One type of electron emitter or cathode which has been used in electron discharge devices is known as "cold" cathode, in that the cathode does not use heat to generate electrons. Rather, the electrons are induced to leave the bulk of the material into the surrounding vacuum by the effect of negative electron affinity (NEA). NEA results when the potential energy level of the conduction band edge in the bulk is higher than the vacuum level at the surface.
Heretofore, "cold" electron emitters have used semiconducting material doped with acceptors to bring the fermi level close to the valence band, thereby maximizing the potential energy of the conduction band edge. NEA results when the surface of these P type semiconductors is coated with a layer of an electropositive work function reducing material, such as alkali or alkaline earth metals.